26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. Each DISTRIBUTION BOX and controller must be grounded. Grounding of the units: Attach a ground wire from one of. There are several factors that make substation grounding absolutely necessary. Safety of Personnel: By safely channeling fault currents into the ground, proper grounding helps to reduce the risk of electric shock to personnel. Preparation: First, you need to prepare some necessary tools, including grounding wire, grounding rod, voltmeter, insulating gloves and insulating tools. The voltage, system arrangement, loads connected, and continuity of.